This invention relates to a multi-mode reproducing apparatus preferably of the electrostatographic type. The apparatus preferably includes means for copying documents selectively at a plurality of magnifications. The apparatus includes an improved system for positioning the optical elements therein for purposes of moving original exposure.
A variety of electrostatographic reproducing machines are commercially employed which have different modes of operation. One type of machine utilizes a moving original exposure system wherein an original document is moved past a fixed slit optical system for projecting an image onto a moving photoconductive surface. These machines include a means for changing the magnification of the projected image and the speed of the moving original to provide reduction copies. The magnification changing systems include various systems for repositioning the optical elements. Exemplary of patents in this area are U.S. Pat. Nos. 3,076,392 to Cerasani et al., and 3,649,114 to Vlach et al.
Other machines have been adapted to copy stationary original documents at a variety of magnifications or reductions through the use of a scanning optical system with different scanning speeds and conjugate changing by repositioning optical elements. Exemplary of patents in this area are U.S. Pat. Nos. 3,476,478 to Rees, Jr.; 3,542,467 to Furgeson; U.S. Pat. No. 3,614,222 to Post; and 3,837,743 to Amemiya.
Another type of variable magnification copier, in which full frame flash exposure is made of a stationary original document, is shown, for example, in U.S. Pat. No. 3,778,147 to E. G. Reedhil et al. It discloses delaying the application of the flash energizing pulse in response to the selected magnification ratio.
The aforenoted machines are adapted to provide one or more modes of copying having different magnifications. Other forms of multi-mode copiers are available commercially. For example, in the Xerox 3100 LDC machine an optical system is provided which enables the machine to copy from a stationary original in a first scanning mode or from a moving original in a second fixed optical mode. This latter mode is particularly adapted for copying documents larger than the conventional viewing platen size. U.S. Pat. No. 3,900,258 to Hoppner et al. [1] is illustrative of a machine similar in many respects to the 3100 LDC machine.
Reproducing apparatuses including the capability of making copies from both moving and stationary originals are also described in U.S. Pat. No. 3,833,296 to Vola, and in IBM Technical Disclosure Bulletin, Vol. 12, No. 1, at page 173, June 1969.
In U.S. applications Ser. No. 549,684 to Bar-on, and U.S. application Ser. No. 598612to Hughes, there are disclosed reproducing machines wherein belt type document feeders are utilized for advancing documents over a platen and past a fixed scanning optical system for providing moving original exposure. In the latter application a moving original exposure mode for reduction copying may be employed.
It has been found desirable, to provide a multi-mode reproducing apparatus having various unique features of the 3100 LDC machine, including its extremely compact size, but also having the capability of reduction copying.
One approach to such a machine is described in U.S. application Ser. No. 588,971 to Hoppner et al. [2]. In that application a multi-mode reproducing apparatus is provided including both moving and stationary original exposure modes, with at least two modes of moving original exposures at differing copy image magnifications.
The particular optical system described in the Hoppner et al. [2] application is similar in most respects to that described in application Ser. No. 588,974 to Spinelli et al. An add reflector is selectively positionable into the optical path to combine with the half-rate mirror to form a reflection cavity and increase the object distance for magnification change. The lens is movable relative to the optical path to adjust the conjugate distance. The add mirror does not form a part of the scanning optical arrangement so that no adjustment is necessitated in the drives of the scanning mirrors irrespective of which magnification mode is selected.
In the apparatus of the Hoppner et al. [2] application, only two modes of moving original exposure are shown although additional modes could be provided. One at a nominal magnification wherein the add mirror is positioned out of the optical path and one at a reduced magnification wherein the add mirror is positioned in the optical path. If it is desired to provide multiple reduction modes, then it would be necessary not only to translate the lens to a still different position, but also to adjust the position of the add mirror to again change the appropriate conjugate.
Another approach to such a machine is described in U.S. application Ser. No. 627,432 to Bierworth et al. In that application a reproducing apparatus is described with plural modes of moving original exposure at different copy image magnifications. A plurality of document viewing positions are provided corresponding to different desired copy image magnifications. The documents are fed past the viewing positions at a velocity which is proportionally synchronized to the velocity of the imaging surface. An optical system for strip-wise viewing the document is positioned selectively at one of the viewing positions for projecting an image thereof onto the imaging surface selectively at one of the plurality of magnifications corresponding to the viewing position.
The viewing and projection system in Bierworth et al preferably comprises an optical means including at least one optical element arranged for movement along a given path to enable it to view the document at any of the viewing positions, and a means for selectively fixing the optical element along the path to view the document at the desired one of the viewing positions. Any desired system could be utilized for positioning the optical elements in this system for purposes of moving original exposure at the selected magnification.
The specific approaches which are disclosed in that application for positioning the optical elements comprise the basis of the present invention along with some additional alternatives which will be described hereafter. The optical element positioning systems of this invention are believed to provide a considerable improvement over prior art systems and are uniquely suited to the application described.
In U.K. Pat. No. 1,336,819 a high speed copier system is disclosed with varying projected image magnifications. Varying magnification is provided by repositioning a lens and mirror using a single drive motor operating through separate slip clutches. The slip clutches allow the motor to continue to drive the lens or mirror even though one of them has been stopped.